Looking for advice on a new project

[Lester Nicholson]

Building a new airplane with an I-beam wing using the same constuction methods as the Neptune and Ares airplanes and would like to know what y'all think about using monokote on the wing. I've been told in the past not to because of the lack of torsional (not even sure what that means)ridgity in this type of wing. Thank you.     Nick

[John Stiles]

Check out Worldtex.....it has the strength of silk and is sure good for stretching around wingtips. Heres a link to check it out: http://www.greathobbies.com/search/results/?srchtype=AdvSearch&srchvendor=WTX&srchcat=AC

[Tim Wescott]

Torsional rigidity is the ability of a structure (like a wing) to resist twisting.  If a wing doesn't have much torsional rigidity, then you can grab a wing tip, give it a twist, and see the wingtip tilt up or down easily as you twist it.  If a wing has lots of torsional rigidity, then you can grab a wing tip and twist it as hard as you want, and it'll never move with respect to the wing root.

Tubes have lots of torsional rigidity, but I-beams don't.  There's really nothing in an I-beam wing to lend any torsional rigidity to the structure until you put the covering on -- then the torsional rigidity is provided by the covering.  Compare this to a D-tube wing, which has a nice continuous tube (if you put in those shear webs) formed by the spars, the shear webs, and the leading edge sheeting.  That wing's wooden structure provides all the torsional rigidity you'll need, so you don't need to ask the covering to provide any.

[Wynn Robins]

I have seen plenty of Ibeam wings covered in film that are just fine - dont know why all the big to-do about it.

[W.D. Roland]

This brings up one of those brain explosion or short circuits or was it that lightning strike?(control line thing)

A possible way to increase the torsional rigidity of wing (and other structures).
Carbon Fiber, thread? rod? strip?  start at center section area attached to spar(or other?) pulled to the
trailing edge at(or near?) wing tip.
Installed before planking/sheeting and cap strips(?)
This would place the CF below the finish level( covering, sanding)

Have never tried this idea, have never built an I beam wing, have never had a good crash.


The high temp films are much less 'stretchy' than low temp film.
I have sometimes double covered center sections out for several ribs past sheeting with 'plastic' to add skin strength(tension)

Coverite Silk Spun iron on is real tuff and should be real good for using skin tension to add torsional rigidity.

Coverite went MIA?

I heard Polyspan is same stuff with out the adhesive?( I have never seen the material)


EDIT
 Wynn
I agree with that.

[Brett Buck]

Building a new airplane with an I-beam wing using the same constuction methods as the Neptune and Ares airplanes and would like to know what y'all think about using monokote on the wing. I've been told in the past not to because of the lack of torsional (not even sure what that means)ridgity in this type of wing.

     I think it's a generally bad idea unless you resort to exotic materials. I know a lot of people like the way they look and they are pretty easy to build but aside from that I think they are about the worst way to go in almost all other respects. I don't think they are nearly stiff enough for me even covered with silkspan/dope. Monokote is (or used to be) a lot better than the other "soft" films but anymore I have no idea what Monokote might do, and the soft films are even more unsuitable.

      Brett

[Bill Little]

I was told by Mr. Bill Werwage to never use any film on an I-Beam model.  He won 2 World Championships with a large I-Beamer, the USA-1  He has probably flown more I-Beam models that most people have ever flown any type of model.  Even when done correctly with good silkspan or silk, the wings can flex a little on an I-Beamer.  Even though some people can get away with it, I wouldn't

Billy's word on an I-Beamer is good enough for me.

Big Bear

[John Stiles]

Here's what the Worldtex looks like, and it will add greatly to the rigidity[if you want it to be shiny and fuel proof you can clearcoat it]:

[don Burke]

Since an I-beamer uses strip ribs, run them diagonal meeting adjacent ones alternating at LE and TE should take care of most of the torsional flex.   Along the LE between adjacent ribs put a couple of half ribs back to the spar.  Doesn't look "traditional" but will work.

[EddyR]

Don is correct,putting the ribs at a angle will make the wing very strong. Building this way is called Warren Truss. This wing will not twist.Even without covering is is just as strong as a D-tube as far as twisting goes. I-Beams can be built with a sheeted trailing edge and they will be much better than a stock I-Beam but it is more work.
EddyR

[John Stiles]

 Here you can get a sample of all "Solartex" colors for $1.00 https://www.balsausa.com/store/category.php?id_category=39

[Lester Nicholson]

Gentlemen, Thank you. I'm startinf w/Ares plans but am making many changes so that I can basicly use what I've got on hand. I  don't intend to spend the first dollar on this project. I have monokote in the shop, thus my question? Built a neptune look alike about 20 years ago and still have the landing gear w/pants and fairing and the canopy. Gonna use these and wood from my scrap box. The picture that Ed posted showed me how to do the wing ribs - and oh, by the way you,ve convinced me as a group to use up my silkspan and dope. Thank you all for your help.   Nick

[FLOYD CARTER]

You asked for good advice, and you got lots of good advice.  You didn't mention that you would ignore all of it and use whatever "junkyard" parts you happen to have.

F.C.

[Tim Wescott]

You asked for good advice, and you got lots of good advice.  You didn't mention that you would ignore all of it and use whatever "junkyard" parts you happen to have.

I dunno -- he said he was going to use Ed's truss structure.

I like getting lots of advise -- that way I can choose the bits that let me do what I was going to do anyway.

[Tim Wescott]

This brings up one of those brain explosion or short circuits or was it that lightning strike?(control line thing)

A possible way to increase the torsional rigidity of wing (and other structures).
Carbon Fiber, thread? rod? strip?  start at center section area attached to spar(or other?) pulled to the
trailing edge at(or near?) wing tip.
Installed before planking/sheeting and cap strips(?)
This would place the CF below the finish level( covering, sanding)

It wouldn't work to just put CF on what's there -- you need to put shear strength on the surface of something that looks like a tube.  This is what Ed's trussed-up I-beamer does, because those diagonal ribs resist shear on the top and bottom surface of the wing.  It's also what a D-tube wing does.

Using a big light tube for the spar may work, but I think the connection between the tube and the ribs would be fragile -- and I think you'd have to be the one to make the tube, and try to keep it light and strong.

[john e. holliday]

If you have Super MonoKote go with it.  Shrunk down properly it will have as much tension as any other covering.  With silk, silk span and poly-span(poly-tissue from CLC) gets it's tension from the dope that is applied.   

[Bill Little]

If you have Super MonoKote go with it.  Shrunk down properly it will have as much tension as any other covering.  With silk, silk span and poly-span(poly-tissue from CLC) gets it's tension from the dope that is applied.   

Hi Doc,

I always respect your thoughts on these things, and you have more experience with the films than I have.  BUT, that has never been the case in my experience.  I have found the films "stretch" more in flight, and that is the problem.  The stretching causes fatigue in the balsa structure.  I could be wrong...........

AND, it probably won't make a difference on a plane that is not repeatedly flown in practice, etc..  Billy flew hundreds of flights will all his contest planes (even documented thousands on some) so maybe that isn't a good comparison on my part.  I just like it better to be safe than sorry sometimes.  If it holds up for Billy for hundreds or thousands of flights, it will definitely hold up for my limited flying.

Bill

[john e. holliday]

My flying partner was having trouble getting the covering(MonoKote) to stop showing wrinkles after each flying session.  I had him bring his plane down to my dungeon at the time.  This has been almost 20 years ago.  I pulled out my iron and started going over the covering.  I thought he was going to lose it when he seen the covering changing colors and getting loose as all get out.  After it cooled he couldn't beleive how tight it was.  Have to make sure the seams are really down before shrinking.  I don't have as many I-Beams under my belt as I would like, but have found them fairly stiff.  I have had the Detroitor,  the Staggerwing Beech and Spitfire by Sheeks.  Maybe I use too stiff balsa in the construction.  I have also found that a wing that is not sheeted on the leading edge will be twistable as an I-Beam.  I think Bobby and Randy have the right idea with the Geo type construction.   And yes I have seen several I-Beamers fold a wing as well as being very flexible while flying.  Guess I over build.  Any way I hope to meet you some day and see some of your planes.   

[John Stiles]

Some of you fellers might want to tray some test pieces of Worldtex....this stuff is A-mazing!